1. Field of the Invention
The present invention relates to a control apparatus and an image forming apparatus, and particularly relates to a control apparatus and an image forming apparatus that generates a second trigger with a delay of a predetermined time from generation of a first trigger.
2. Description of Related Art
In paper carriage control in a conventional image forming apparatus, a CPU operates based on a constant frequency, and controls driving of a motor in response to an output from a sensor. Specifically, the CPU checks the sensor in every processing cycle, and when the output of the sensor changes, the CPU drives the motor after the elapse of a time equal to an integral multiple of the processing cycle.
Incidentally, in the conventional image forming apparatus, it is necessary to heighten the operation frequency of the CPU for the purpose of improving the accuracy of the paper carriage control. In this case, the use of a high-priced CPU is required, which leads to an increase in manufacturing cost of the image forming apparatus.
As an apparatus to perform control similar to the paper carriage control of the image forming apparatus, an image reader described in Japanese Patent Application Laid-Open No. 1110-322517 is known. In the image reader, a CPU generates phase switching data by interruption of a motor timer. A delay circuit counts a predetermined number by use of a counter, and thereafter outputs the phase switching data to a motor port. This allows the motor port to drive the motor with a delay of a predetermined time from the interruption of the motor timer.
However, in the image reader described in Japanese Patent Application Laid-Open Publication No. H10-322517, during counting of the predetermined number, a count value of the counter may exceed the countable upper limit of the counter. In this case, the image reader described in Japanese Patent Application Laid-Open No. H10-322517 cannot operate accurately.